Filter and needle assembly incorporating the filter

ABSTRACT

A needle assembly for removing fine impurities contained in a pharmaceutical preparation or blood to be administered through the needle assembly into a human body, comprising a filter which consists of a wad of at least one lengthy filament of synthetic resin which is intricately and uniformly entwined into the wad form.

United States Patent Ishikawa Jan. 14, 1975 [5 FILTER AND NEEDLE ASSEMBLY 2,864,366 12/1958 Miskel 128/221 INCORPORATING THE FILTER 3,093,583 6/1963 Stoll 210/496 X 3,448,041 6/1969 Swank 1 210/496 X Inventor: J I w y Japan 3,757,780 9/1973 lshikawa 128/221 x [73] Assignee: lshikawa Manufacturing Co.,

Tokyo Japan Primary Examiner-Richard A. Gaudet [22] Filed: May 31, 1973 Assistant Examiner-J. C. McGowan [21] AppL NOJ 365,738 Attorney, Agent, or FirmEric H. Waters [30] Foreign Application Priority Data June 6, 1972 Japan 47-55595 ABSTRACT [52] US. Cl. 128/218 N, 128/221 A needle assembly for removing fine impurities con- [51] Int. Cl A61m 5/32 tained in a pharmaceutical preparation or blood to be [58] Field of Search 128/221, 218 N, 215, 216, administered through the needle assembly into a 128/214 R, 214 C, 214 F, 2 F, 272, 276, 218 human body, comprising a filter which consists of a R, 218 D, 218 M, 220, 218 NV; 210/496, 23 wad of at least one lengthy filament of synthetic resin which is intricately and uniformly entwined into the [56] References Cited wad form.

UNITED STATES PATENTS 2,783,609 3/1957 Breen 210/496 UX 4 Claims, 8 Drawing Figures FILTER AND NEEDLE ASSEMBLY INCORPORATING THE FILTER.

The present invention relates to a medical needle assembly such as a hypodermic syringe or a venoclysis equipment for introducing a medicament or blood into the human body.

Extreme precautions are taken to prevent pharmaceutical preparations from becoming contaminated before they are injected or infused into the human body, but there still exist possibilities that impurities may be introduced into the preparations during the administering processes. These particles may be introduced into the preparations when, for example, the ampoules or breakable cartridges containing the preparations are ruptured or punctured or when, for example, the fluid conducting tubings are fitted to the rubber plugs of the reservoirs of the venoclysis equipment. The fine fragments of the materials forming the ruptured container of the preparation or the rubber plug may find their way through the administering system into the blood stream of the human body.

Various filter means have therefore been proposed and put into practice for the purpose of removing the thus produced impurities from the medicaments before the medicaments are discharged from the needles or cannulae of the administering equipment. Typical examples of the prior art filter means adapted to achieve this purpose will be the one formed of staple fibres pressed or otherwise configured into a lump form and the one formed of nylon fabrics or sintered nylon powder. During use of these filters, it frequently happens that relatively short fibres are separated from the lump or fabrics or minute fragments fractured or torn apart from the sintered powder and are consequently entrained in the preparations passed through the filter means. While the impurities initially contained in the preparationspassed to the filter means may be collected by the filter means at satisfactory efficiencies, the preparations which have passed through the filter means thus contain other impurities that result from the fibres or fragments separated from the materials forming the filter means. The present invention contemplates elimination of these drawbacks inherent in the prior art administering needle assemblies.

In accordance with the present invention, there is provided an administering needle assembly which comprises a first bored member having a longitudinal bore for conducting fluid .therethrough, a second bored member disengageably fitting at one end on the first bored member and having a longitudinal bore extending throughout its length and in communication with the bore in the first bored member, a needle securely connected at one end to the other end of the second bored member and having an axial bore extending throughout its length and in communication with the bore in the second bored member, and a filter which comprises a wad of at least one length of continuous filament of synthetic resin substantially uniformly entwined into the wad form and which is located in a passageway formed through the aligned bores in the first and second bored members, the filament having a denier number ranging'from about 75 to about 150 and the wad of the filament having a density ranging from 0.8 gram/cm to about 1.6 gram/cm. Preferably, the denier number of the filament may range from about 75 to about 85 and, in this instance, the density of the a second bored member and the needle which are usually disposable as a unit.

Other features and advantages the administering needle assembly according to the present invention will become apparent from the following description taken in conjunction with the accompanying drawings in which:

FIG. 1 is a perspective view showing a wad of a filament wound on a spindle during a process to form the filter to be incorporated into the needle assembly according to the present invention;

FIG. 2 is a perspective view of the wad of the filament released from the spindle illustrated in FIG. 1;

FIG. 3 is a longitudinal sectional view showing a preferred embodiment of the needle assembly incorporating the filter of the initial configuration illustrated in FIG. 2;

FIG. 4 is a perspective view of another form of filter which may be incorporated into the needle assembly embodying the present invention;

FIG. 5 is a longitudinal sectional view showing a preferred embodiment of the needle assembly incorporating the filter of the configuration illustrated in FIG. 4;

FIGS. 6 and 7 are fragmentary longitudinal sectional views of still other preferred embodiments of the nee dle assembly according to the present invention; and

FIG. 8 is a longitudinal sectional view showing part of still another preferred embodiment of the needle assembly according to the present invention.

Referring to FIG. 1, the filter to be incorporated into the needle assembly proposed by the present invention is comprised of at least one length of continuous filament 10 of synthetic resin. The filament 10 may be extruded in a heat-plasticized condition from an orifice in a usual extrusion die (not shown) and wound, when set, on a spindle 12 into the form of a roll 14 of a desired diameter. The spindle 12 should then be removed from the roll 14 of filament so as to allow the filament 10 to entwine on itself into the form of a wad 16 shown in FIG. 2. The filament 10 will become entangled more intricately and uniformly when the wad 16 is forced under pressure into a working position. The entanglement of the filament 10 may be enhanced and consequently the density of the wad 16 made more uniform where the filament is extruded or otherwise afterwards processed to a curled condition. Generally, the density of the wad 16 of filament will vary with the fineness (which is herein indexed in terms of the denier number) and the length of the filament and/or the pressure with which the wad 16 is forced into the working position.

FIG. 3 illustrates an embodiment of the medical administering needle assembly incorporating the filter thus comprised of the wad 16 of the filament 10. The needle assembly is herein shown as a hypodermic syringe of Leur-type including a syringe barrel 18 having a longitudinal bore 20, and a plunger 22 longitudinally slidably received in the bore 20. The syringe barrel 18 has formed at its leading end a snout 24 tapering toward its tip. A needle holder 26 has .a bore 28 tapering toward its reduced end to match the tapering snout 24 of the syringe barrel 18 so that the needle holder 26 can be press fitted on the snout 24 through its tapering bore 24. The needle holder 26 carries at its reduced end a needle 30 having a piercing point 32 and a passageway (not shown) extending throughout its length as is customary. The configuration of the hypodermic syringe above described is merely for the purpose of illustration and, as such, the syringe may have any other configuration which is in common use or which may be modified therefrom.

In accordance with the present invention, the wad 16 of the filament 10 formed in the manner previously described is positioned at the leading end of the bore 20 in the syringe barrel l8, viz., immediately anterior to the snout 24.The wad 16 of the filament 10 will thus serve as a filter to remove impurities entrained in a pharmaceutical preparation or blood to be administered through the syginge barrel 18. The wad 16 is forced into the syringe barrel 18 by a pressure selected to provide a desired density of the wad finally positioned in the barrel.

FIG. 4 illustrates another preferred configuration of the filter of the needle assembly according to the present invention. Referring to FIG. 4, the filter comprises a bobbin 34 having a pair of spaced flanges 36 and 36 and a shaft or cross member which is connected or integral at its ends with the flanges 36 and 36' of a predetermined diameter. The flanges 36 and 36 are formed with suitable members of apertures 40 and 40', respectively, which are preferably in alignment with each other as illustrated. The bobbin 34. thus constructed is usually formed of a plastic material .but, where desired, it may be formed of metal. The shaft or cross member carries thereon a roll 14 of at least one length of continuous filament of synthetic resin which is entwined substantially uniformly. The roll 14 of filament may be formed in such a manner that the filament l extruded from an orifice in a usual extrusion die (not shown) is wound irregularly on the shaft or cross member until the resultant roll of filament has a diameter which is substantially equal to the diameter of the flanges 36 and 36'. Where the filter is prepared in this manner, the density of the roll 16 of the filament will vary not only with the fineness and length of the filament but the tension at which the filament is wound on the bobbin 34. The density of the roll 14 of the filament 10 may therefore be selected through proper adjustment of the tension with which the filamentis wound on the bobbin 34 during preparation of the filter.

FIG. 5 illustrates a hypodermic syringe incorporating the filter of the configuration illustrated in FIG. 4. The syringe is shown as constructed similarly to that illustrated in FIG. 3 and thus the corresponding parts in both figures are designated by like reference numerals. Referring to FIG. 5, the filter consisting of the bobbin 34 and the roll 14 carried thereon is positioned at a leading end portion of the longitudinal bore in the syringe barrel 18. The fluid to be administered from the syringe barrel 18 or sucked in through the needle 30 is passed through the roll 14 of the entwined filament in the bore 20 through the apertures in one of the flanges 36 and 36' of the bobbin 34 and emerges from the roll 14 through the apertures in the other of the flanges, whereby the particles contained in the fluid are collected in the entwinements of the filament forming the roll 14.

The filter incorporated into the needle assembly according to thepresent invention has thus far been as sumed as being locatedwithin the elongated bore 20 in the syringe barrel 18 by way of example. In order to facilitate the use of the syringe to exchangethe used filter with a new one simultaneously when he exchanges the needles, it will be advantageous to have the filter located within the needle holder 26 which is disengageably fitted to the snout 24 of the syringe barrel 18 in each administering process. FIGS. 6 and 7 illustrate embodiments of the hypodermic syringe arranged in this manner, wherein only the snout portion 24 and the needle holder 26 complete with the needle 30 are indicated. Thus, FIG. 6 shows the embodiment in which the filter consisting of the wad 16 prepared in the manner illustrated in FIGS. 1 and 2 while FIG. 7 shows the embodiment in which the filter comprising the roll 14 of the filament wound on the bobbin 34 as illustrated in FIG. 4. Ineither of the embodiments shown in FIGS. 6 and 7, the filter is located within the tapering bore 28 in the needle holder 26, viz., intermediate between the tip of the snout 24 on the syringe barrel 18 and the leading end of the tapering bore 28 in the needle holder 26. Where desired, the needle holder 26 may be provided with a generally frusto-conical ring member 42 inserted into the open end portion of the needle holder 26 as seen in FIG. 7. The frusto-conical ring member 42 has an outer peripheral surface tapered to match the inner peripheral surface of the needle holder 26 and an inner peripheral surface tapered to match the outer peripheral surface of the snout 24 of the syringe barrel 18. The filter in the needle holder 26 thus intervenes between the ring member 42 and the leading end of the needle holder 26 so as to prevented from being moved out of the bore 28 in the holder 26. The provision of the ring member 42 will be advisable where the filter according to the present invention is to be supplied as a unit complete with the needle and the needle holder to the user of the needle assembly.

While the filter has been described as being incorporated in the hypodermic syringe, the same may be used in a venoclysis equipment by which a pharmaceutical preparation is infused under pressure of gravity into the human body at a limited rate. The venoclysis equipment generally includes a fluid container having a fluid outlet at its bottom in the operating position of the equipment. A flexible tubing leads directly or through a suitable fluid reservoir from this outlet and terminates in an adapter which is usually in the form of a bored tubular member. The adapter is fitted at one end to the leading end of the flexible tubing so that the fluid from the container is conducted thereto through the flexible tubing. Referring to FIG. 8, the adapter is designated at 44 and is shown as having a hollow swell 44a as customary. The adapter 44 has a forwardly pairing snout 46 projecting from the leading end of the adapter 44. A needle holder 48 has an axial bore 50 which is tapered toward its leading end to match the tapered outer peripheral surface of the snout 46. The needle holder 48 is snugly yet disengageably received on the snout 46 through its axially tapering bore 50 as illustrated. The needle holder 48 carries at its end opposite to the snout 46 a needle or cannula 52 having a piercing point 54 as usual.

In the venoclysis equipment arranged as above described, the filter according to the present invention is positioned within the bore 50 in the needle holder 48, viz., intermediate between the leading end of the needle holder and the tip of the snout 46 projecting into the bore 50. The filter is herein illustrated by way of example as being in the form of the wad 16 of the entwined filament prepared in the manner previously described. Where preferred, however, the filter of the configuration illustrated in FIG. 4 may be used in lieu of the wad 16 of filament. It is apparent that the filter of either of these configurations may be located, where desired, in the bore (not shown) in the adapter 44 intermediately upstream of the snout 46.

The advantages of the filter and the needle assembly incorporating the needle in accordance with the present invention will be more apparently understood from the following examples:

Example 1 A single continuous filament of cellulose acetate was extruded from an orifice of a known extrusion die to a denier number, of 75. The filament, measuring 3,500 mm in length, was wound with a tension of 4 grams on a spindle of a diameter of 1 mm into a roll measuring 4 mm in diameter and 3 mm in axial length and the resultant roll of filament was removed from the spindle so as to form a wad of entwined filament weighing 29.2 milligrams. The wad of filament was then stuffed by the use of a sterilized glass rod into the bore, measuring 3 mm in diameter, of a needle holder of a usual venoclysis equipment with a pressure selected to achieve a density of 0.77 gram/cm A total of ten specimens of the filter were prepared and respectively mounted in the venoclysis needle holders in similar manners. 500 millilitres of distilled water contained in the fluid container bottle of each venoclysis equipment was dripped for about 30 to 40 minutes through the needle holder into a glass beaker which had been perfectly sterilized. Particles contained in the water thus transferred to each beaker were counted by the class of overall diameter through microscopic observation. Table 1 indicates the results of these tests.

A total of filters were prepared each from a single continuous filament of cellulose acetate of a 85 denier number and a length of 3,500 mm in manners similar to those of Example 1. Each of the filters was thus in the form of a wad measuring 4 mm in diameter and 3 mm in axial length and weighing 33.1 milligrams. Each wad was then mounted in a needle holder of a venoclysis equipment similar to those used in Example 1, achieving a density of 0.87 gram/cm. Tests were conducted to examine the performances of the filters incorporated in these needle holders with the results indicated in Table 2.

Table 2 Spec- Total Diam. of Particles (microns) imen Number of No. Particles 24 25-49 58-99 100 1 l9 l7 2 0 0 2 l5 l2 3 0 0 3 l3 12 l 0 0 4 l8 l6 2 0 0 5 l4 l0 4 0 0 6 7 7 0 0 0 7 l0 9 l 0 O 8 l l l l O O O 9 l7 l5 2 0 0 l0 7 7 0 0 0 Total 11H 1 l6 l5 0 0 Example 3 A single continuous filament of cellulose acetate was extruded to a denier number of 85 and in a length of 3,500 mm. The filament was then wound with a tension of 4 grams on a bobbin having spaced flanges of a diameter of 4 mm and a shaft of a diameter of 1 mm and a length of 3 mm, forming a roll measuring 4 mm in diameter and 3 mm in axial length and having a density of 0.87 gram/cm". A total of ten of such a filter were prepared and respectively mounted in venoclysis needle holders similar to those used in Example 1. Tests similar to those of Example 1 were then conducted with these filters in the venoclysis equipments, the results of the tests being demonstrated in Table 3.

To compare the performances of the filter according to the present invention with known filters formed of fine filaments, similar tests were conducted with specimens each consisting of fabrics woven to pore sizes of approximately 25 microns. These specimen included ten of the filters (called specimens A) formed of nylon fibres of denier number and 10 of the filters (called specimens B) formed of nylon fibres of denier number. The results of these tests are indicated in Tables 4 and 5.

Table 4 No. of Total Diam. of Particles (microns) Speci- Number of mens A Particles 24 25-49 58-99 l 68 57 l l 0 0 2 53 39 14 0 0 3 74 59 ll 3 0 4 6O 50 9 l 0 5 54 46 7 l 0 6 32 28 4 0 O 7 29 l6 l3 0 0 Table 4-Continued No. of Total Diam. of Particles (microns) Speci- Number of mens A Particles 24 25-49 58-99 100 8 31 2i 9 l 9 63 53 10 0 0 1O 55 42 l l 2 0 Total 519 411 100 8 0 Table No. of Total Diam. of Particles (microns) Speci- Number of mens B Particles 24 25-49 58-99 100 l 75 62 13 0 0 2 58 39 17 2 O 3 80 65 14 l O 4 52 43 9 0 0 5 49 39 9 1 O 6 26 21 4 l 0 7 79 64 l4 1 0 8 28 25 3 0 0 9 48 46 l l 0 10 57 44 l2 1 0 Total 552 448 96 8 0 Similar tests were further conducted with commonly used filters including those of compacted staple fibres and those of sintered nylon powder. Table 6 shows the results of these tests.

From comparison between Tables 1 to 6, it will be apparent that the filter according to the present invention has a significantly greater ability of filtering fine particles contained in fluid than that of the filters which are conventionally in common use. While the particles of the diameters larger than 50 microns can be perfectly filtered, the filter according to the present invention especially features an ability to strain the impurities of the diameters smaller than 25 microns. The filter herein proposed is thus expected to greatly contribute to the purification of medicaments and blood to be administered into human bodies although the same will find practical applications in various other fields such as, for example, for removing impurities from chemical solutions in laboratory experiments.

For the purpose of determining optimum denier numbers of the filaments'to form the filter according to the present invention, the filters of the configuration illustrated in FIG. 1 were prepared from filaments of denier numbers of 70, 75, 80, 85, 100, 120, 140, 150 and 160. These filters were placed on tests under the conditions similar to those mentioned in Example 1. Table 7 indicates the results of the tests.

From this table, it will be seen that the denier number of the filament to form the filter according to the present invention is acceptable in a range of from about to about 150 and is particularly preferable in a range of from about 75 to about 150. According to the experiments conducted by the inventor, it has revealed that, if the filament forming the filter has a denier number less than 75, clogging of the filter occurs by reason of an increased density and thus invites deterioration of the filtering efficiency, let alone the cumbersomeness which is likely to be involved in preparing the filter from such a fine filament. If, on the contrary, the denier number of the filament exceeds 150, the filter formed of such a filament would be unable to retain relatively fine particles and wouldconsequently fail to exploit the advantages of the filter according to the present invention. Where the filament having the fineness of the above specified range is wound into the roll form with a tension approximating 4 grams applied thereto, the resultant wad will possess a tension ranging from about 0.8 gram/cm to about 0.9 gram/cm if the filament forming the wad has a denier number of from about 75 to about or from about 0.8 gram/cm to about 1.6 gram/cm if the filament has a denier number of from about 75 to about 150. Thus, the density of the wad forming the filter according to the present invention is acceptable in the range of from about 0.8 gram/cm to about 1.6 gram/cm and is preferable in the range of from about 0.8 gram/cm to about 0.9 gram/cm as previously mentioned.

What is claimed is:

1. A medical administering needle assembly comprising a first bored member having a longitudinal bore for conducting fluid therethrough, a second bored member disengageably fitted at one end thereof on said first bored member and having a longitudinal bore extending throughout its length and in communication with said bore in the first bored member, a needle having one end securely connected to the other end of said second bored member and having an axial bore extending throughout its length and in communication with the bore in said second bored member, and a filter which comprises a wad of at least one length of continuous filament of synthetic resin substantially uniformly entwined into wad form and located in a passageway formed between the axially aligned first and second bored members, said filament having a denier number ranging from about 75 to about and said wad of the filament having a density in a range of from about 0.8 gram/cm to about 1.6 gram/cm.

density in a range from about 0.8 gram/cm to about 1.7 gram/cm.

4. A medical administering needle assembly as claimed in claim 1 in which said filament is curled. 

1. A medical administering needle assembly comprising a first bored member having a longitudinal bore for conducting fluid therethrough, a second bored member disengageably fitted at one end thereof on said first bored member and having a longitudinal bore extending throughout its length and in communication with said bore in the first bored member, a needle having one end securely connected to the other end of said second bored member and having an axial bore extending throughout its length and in communication with the bore in said second bored member, and a filter which comprises a wad of at least one length of continuous filament of synthetic resin substantially uniformly entwined into wad form and located in a passageway formed between the axially aligned first and second bored members, said filament having a denier number ranging from about 75 to about 150 and said wad of the filament having a density in a range of from about 0.8 gram/cm3 to about 1.6 gram/cm3.
 2. A medical administering needle assembly as claimed in claim 1, in which said filament has a denier number in a range of from about 75 to about
 85. 3. A medical administering needle assembly as claimed in claim 1 in which said wad of filament has a density in a range from about 0.8 gram/cm3 to about 1.7 gram/cm3.
 4. A medical administering needle assembly as claimed in claim 1 in which said filament is curled. 